1. Technical Field
The present invention relates to a liquid discharging apparatus, a head unit provided in a liquid discharging apparatus, and a control method of a liquid discharging apparatus.
2. Related Art
A liquid discharging apparatus such as an ink jet printer executes a printing process of forming an image on a recording medium by driving and displacing a piezoelectric element provided in a discharging unit using a driving signal to discharge liquid such as ink, with which a cavity (pressure chamber) in the discharging unit is filled, from a nozzle of the discharging unit.
In such a liquid discharging apparatus, a discharge abnormality in which liquid cannot be properly discharged from the discharging unit may occur due to an increase in viscosity of liquid or due to air bubbles intruding into the cavity. Furthermore, when a discharge abnormality occurs, dots which are scheduled to be formed on a medium by liquid discharged from the discharging unit cannot be formed accurately, which causes a decrease in quality of an image formed by the liquid discharging apparatus.
JP-A-2004-276544 suggests a technique of preventing a decrease in image quality due to a discharge abnormality in which residual vibration generated in a discharging unit is detected after a piezoelectric element is driven by a driving signal and a liquid discharge state of the discharging unit is determined on the basis of the result of the detection.
Incidentally, residual vibration generated in the discharging unit is detected as an electromotive force of the piezoelectric element. However, since the amplitude of an electromotive force of the piezoelectric element which is generated by the residual vibration is small, there is a problem that it is not possible to accurately determine an ink discharge state in a case where noise is superimposed on a signal indicating the electromotive force of the piezoelectric element.